All you intelligent guys forgot to mention forest fires. The climate on the earth is changing and "Mega" also called "Seige" fires are occuring, some feel because of Global Warming. Hotter fires are making them harder to control thus burning 500,000 acres or more at a time. These fires are 10 times larger then forest fires we have had 20 years ago. Some of these areas are going to take a generation or more to recover. Trees that used to able to withstand some fires are incinerating with the new "Mega" Hot Fires. This is partly caused by early Springs and snow melts. I'm not sure it is all caused by Carbon Monoxide releasd by vehicles but it's probably playing a part. See program on the CBS website "The Age of Mega-Fires" 12/30/07.
